I'll try to remember some of my favorites...
tfgamessite.com hosts most of the games that I can think off. Most of them have transformation, or transgender themes, so if that's not your thing, you can ignore this list. Of course they're not limited to these themes, TF/TG just tends to be the central theme of the content.
"Beth" is a really fun mind trip with decent erotic content. It surprises you with decent characterization, and has half a dozen endings or so. Should take you 3 hours or so to finish. It's worth playing just for the novelty of it, but isn't on par with the rest on this list.
Press Switch and Student Transfer are both excellent visual novels that feature highschool aged body swaps. Both of them have fun characters, and decent convoluted story lines in addition to the good erotic content with images. The biggest problems is that the Chinese cartoon element could be a turn off, and both of them only have one or two endings with a lot of incomplete story lines.
I really like the traditional jrpg style games like Ascenda's Descent (Which is basically dead no matter what people on the forums say But it's damn good... I mean damn good in all elements of gameplay and story content.) Miss Adventures of Fred Ace (which is more of a comedic misadventure with erotic BDSM content. ) Monline (SAO/ .Hack TF/TG rip off, but has a ton off bad endings and fun story archs) Alone Amongst Demons (Fun story that's oddly sweet despite the overt corruption themes.) Runes of Chaos (Which starts really slowly, but becomes a good story as you continue last I checked it was very imbalanced though.)
And of course there's literally over a hundred erotic escape/ trapped/ puzzle themed rpgmaker games, but the ones that stand out in my mind as the best are Halloween Party Seance and Prisoners of the Elder One. Both of these have a ton of bad endings, a ton of transformations, solid erotic content, creative gameplay, and fun stories to boot.
Tales of the Drunken Cowboy is a great erotic game featuring subtle mind control without character death. It's just quality stuff. Similarly The Hers Project. has some high quality stuff and sets the platform for an excellent game. Unfortunately it only ever completed 2 or 3 of the 7 or so cells you are supposed to be able to explore.
I would also suggest the Corruption of Champions prisoner expansion by
feifongwong. It takes an earlier version of CoC (Right about when Fenoxo was working on the prairie if I recall correctly.) and tacks on a prison element, where you can get captured and made a slave. It's got a few good solid hours of story content, and if you play a lot of erotic games, you will see that quite of few of them copy a lot of the content in this expansion. Unfortunately it seems lost to time, never to make it past the first mission of level three.
Cursed deserves to be on these lists if only because of the sheer size of it, though perhaps not quality of erotic content. It's been described as the first true magical TG life simulator, and it really is good, it just doesn't have many overtly erotic encounters. It's more about the daily grind of living with crazy TF's like hiding cat ears from your boss or trying not to piss of the crazy witch that transformed you, all while finding a job where you don't turn into a slut. Coming in the wake of cursed is the Elf Parlor, and Ideal Intentions. Both introduce some very solid mechanics, but are thus far in progress and don't feature much content.
Masculine Mystique is an immense TG/ TF reactive story (I say reactive because CYOA or interactive fails to describe how immersive, and how responsive this game is.) set in a more realistic environment. None of the outlandish magic, and a ton of encounters. Despite it's relatively short length, it has more content than can be discovered in dozens of hours. It centers around a protagonists struggle with "The Process" at his new school, which changes the subject to match their physical and sexual ideal of male / female and dominance/ submission. Every tiny action changes the story in a unique way, and it features a ton of great hidden paths including everything from hypnosis, to chastity, to bondage, and more. This one focuses more on the usual less outlandish aspects of eroticism like... you know... making out and sex and exhibitionism stuff instead of wild and strange TF stuff.
There's a ton of great little stories out there too that don't quite deserve the title "game." And I could make another equally large post just talking about that. But this is the best of the best in my opinion.